Understanding KB and MB When Preparing Images for Facebook Posts

Updated March 23, 2026 · 7 min read

Size limits are written in kilobytes and megabytes, and the units trip people up. Facebook re-encodes uploads, and starting from a clean, right-sized JPEG gives it less room to introduce blocky artefacts.

Recommended settings for Facebook posts

SettingStarting point
FormatJPEG (WebP where accepted)
Widthabout 2048 px on the long edge
Quality78
File size400 KB or less

These are practical defaults. If the platform or form you are using publishes its own limits, follow those instead.

Understanding KB and MB When Preparing Images

One megabyte is roughly 1000 kilobytes, and some systems count 1024. If a limit says 100 KB, aim a little under, such as 95 KB, to be safe.

For Facebook posts, a target of 400 KB is a comfortable default. Our results panel shows the exact size of each compressed file so you can confirm it before uploading.

Step by step with TheCompressJPEG

  1. Open the compress JPEG to 300 KB tool, or the main compressor for custom settings.
  2. Drop in your image. Nothing is uploaded; it is processed in your browser.
  3. Set the maximum width to 2048 and the target size to 400 KB.
  4. Press Compress, check the result and download it.
Ready to try it? Compress your JPEG to 300 KB now. It's free and private.

Quick tips

  • Check the result on a phone, where most people will see it.
  • Use consistent dimensions for a set of related images.
  • Resize before you compress; it improves quality at any file size.
  • Write a size limit slightly below the stated maximum to leave a margin.

FAQ

What JPEG quality should I use for e-learning courses?

Quality around 78 keeps photos looking natural while cutting file size substantially.

Will compressing reduce image quality for e-learning courses?

Some detail is removed, but at sensible settings the difference is not visible at normal viewing size.

How do I compress many images for e-learning courses at once?

Drop all of them into the tool together and use Download all to get a single ZIP.

Wrapping up

For Facebook posts, the reliable recipe is simple: resize to around 2048 pixels, compress at quality 78 or to a 400 KB target, and check the result before you upload. Keep the original so you can always start again.

Related guides